What causes an index to become unusable?
What causes an index to become unusable?
Indexes can become invalid or unusable whenever a DBA tasks shifts the ROWID values, thereby requiring an index rebuild. These DBA tasks that shift table ROWID’s include: Table partition maintenance – Alter commands (move, split or truncate partition) will shift ROWID’s, making the index invalid and unusable.
How do I make an index usable again?
Making an Index Unusable When you make an index unusable, it is ignored by the optimizer and is not maintained by DML. When you make one partition of a partitioned index unusable, the other partitions of the index remain valid. You must rebuild or drop and re-create an unusable index or index partition before using it.
How do you find unusable indexes?
Check unusable and not valid Index in Oracle Query will cover the complete index with partition index and sub partition index. Result will give you the rebuild command of invalid or unusable index. You can directly run that and on sqlplus and make them valid or usable state. WHERE STATUS=’UNUSABLE’;
How do you find the index of the unusable state?
Invalid indexes can be checked with a SELECT * from USER_INDEXES WHERE STATUS = ‘INVALID’; SQL statement….You can:
- Drop the specified index and/or recreate the index.
- Rebuild the specified index.
- Rebuild the unusable index partition.
How do you find the unusable index?
Can we disable index in Oracle?
To disable an index, you run an ALTER INDEX command: ALTER INDEX index_name ON table_name DISABLE; You can replace the index_name with the name of your index, and the table_name with the name of the table that the index is created on. This will disable the index on your database.
What happens when an index is marked as unusable?
When one partition of a partitioned index is marked unusable, the other partitions of the index remain valid. An unusable index or index partition must be rebuilt, or dropped and re-created, before it can be used. Truncating a table makes an unusable index valid. When you make an existing index unusable, its index segment is dropped.
How do I Mark an index or index partition as unusable?
You can create an index in the unusable state, or you can mark an existing index or index partition unusable. In some cases the database may mark an index unusable, such as when a failure occurs while building the index. When one partition of a partitioned index is marked unusable, the other partitions of the index remain valid.
What is index unusable state in SQL?
Any SQL statement that tries to use an index that is in an Index Unusable state returns an error. The following conditions cause a direct path load to leave an index or a partition of a partitioned index in an Index Unusable state: SQL*Loader runs out of space for the index and cannot update the index.
How do I use invisible indexes?
Using invisible indexes, you can do the following: Test the removal of an index before dropping it. Use temporary index structures for certain operations or modules of an application without affecting the overall application. Add an index to a set of columns on which an index already exists. What are you really trying to achieve?
